Spectroscopic investigation of europium chalcogenides with emphasis on light scattering by magnons

Metawe, F. M.

Report

FZJ-2016-07015

Spectroscopic investigation of europium chalcogenides with emphasis on light scattering by magnons

Metawe, F. M. (Corresponding author)FZJ*

1979
Kernforschungsanlage Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Kernforschungsanlage Jülich GmbH Zentralbibliothek, Verlag, Spezielle Berichte der Kernforschungsanlage Jülich 50, 127 p., Anh. (1979)

Please use a persistent id in citations: http://hdl.handle.net/2128/13091

Report No.: Juel-Spez-0050

Abstract: Brillouin spectroscopy was for the first time applied to the investigation of inelastic light scattering from thermal acoustic spinwaves in EuO, EuS, Eu$_{0.91}$Gd$_{0.09}$S single crystals and EuS thin films. The experiments were performed with a five passed Fabry- Perot interferometer. The samples were cooled below their Curie temperatures. The frequencies of the inelastically scattered light as a function of the applied magnetic field have been investigated. The spectra show two peaks which can be shifted under the effect of an external magnetic field. One of these peaks was found to be due to a bulk spinwave of the material. The other peak was identified as due to a surface spinwave with nonreciprocal behaviour. It is identical with a surface wave theoretically described by Darnon and Eschbach /18/. This is the first time that light scattering from surface spinwaves has been found. The question is investigated whetherin the present case the frequencies of the spinwaves are properly described by theory. Furthermore thin filrns of EuS and EuGdS have been investigated by rneans of optical transrnission and reflection spectroscopy. The transrnittance and reflectance rneasurementswere carried out at normal incidence, room temperature and in the spectral range between 400 nm and 2500 nm. A computationalrnethod was used to calculate the refractive index and the absorption coefficient. This method includes the correction for multiple beam reflections. Also, the metallic behaviour due to doping EuS with Gd was studied. This replacernent of Eu$^{2+}$ by Gd$^{3+}$ contributes conduction electrons to the lattice which gives rise to strong optical absorption in the near infrared region.

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